1. Field of the Invention
The present invention relates to a reflection detection apparatus that externally emits detection light from a light-emitting surface (display surface of display apparatus) and receives the reflected detection light by a plurality of light-receiving devices, and a reflection detection method. The present invention also relates to a display apparatus and an electronic apparatus including the reflection detection function.
2. Description of the Related Art
A reflection detection generally involves irradiating light onto an object and detecting presence/absence of the objected by detecting reflected light.
However, not only for detecting the presence/absence of an object, but the reflection detection is also used for a position detection for detecting an in-plane position of an object in some cases.
For example, there is known a display device including an optical position detection function, in which a light-receiving device for detecting a designated position is incorporated into a display panel (see, for example, Japanese Patent Application Laid-open No. 2006-301864; hereinafter, referred to as Patent Document 1).
In the technique disclosed in Patent Document 1, a sensor (light-receiving device) that senses light is provided at a part of pixels on a screen or all the pixels on the screen, on a display panel such as a liquid crystal panel and an organic EL panel. By associating a detection signal from the sensor with positional information of a pixel at which the sensor is provided, an in-plane position of an object such as a finger and a pen that has touched a panel surface can be detected. Light that is irradiated onto the object and detected by the sensor is invisible light such as infrared (IR) light. The use of invisible light enables a position detection to be performed even in a screen area in black display or the like.
On the other hand, as a method of measuring a distance between a light-emitting surface of detection light and an object, there is known a triangulation method that is carried out for automatic focusing of a camera apparatus, and the like.